1. Technical Field
The present invention relates to an apparatus and method for directive antenna beam selectivity for high speed wireless communication systems.
2. Description of Related Art
Personal communication systems, indoor wireless networks and mobile cellular radio networks are rapidly growing and developing communication systems. Natural phenomena, such as multipath distortion, signal amplitude degradation and signal interference, which occurs during transmission, limit practical current data transmission rates to about 10 Mbps which is suitable for current needs. However, projections for future communication systems suggest that this 10 Mbps data rate may not be adequate to accommodate the volume of data expected to be transmitted on such systems. In order to increase the data transmission rates, communication systems having the capability to overcome such natural phenomena are necessary.
One attempt to increase the data rates has been to combine antenna elements with adaptive combiners. In addition, techniques have been implemented for analyzing the signal quality for various antenna elements and for selecting between the best combination of transmitter and receiver antenna sectors so as to improve the signal-to-noise ratio and reduce the signal interference and the multipath distortion. However, such techniques for sampling and selecting the proper strategies typically require active elements, such as low noise preamplifiers for receivers and/or high gain amplifiers for transmitters, at each antenna element. Moreover, employing highly directive adaptive antenna arrays for remote transmitters and receivers with a large number of active elements, significantly increases the cost of the transmitters and receivers, in particular, transmitters and receivers which operate in the millimeter frequency spectrum.
In addition, the criterion analyzed to determine the best transmission path is the signal amplitude. For instance, an article entitled "Enabling Technologies for Wireless In-Building Network Communications--Four Technical Challenges, Four Solutions" by Thomas A. Freeburg describes an antenna having six equal 60.degree. directional antennas used to transmit and receive data. Signal sampling and selection protocol identifies the best signal relationship between transmitter and receiver sectors for each individual data transmission. The criterion used by the sampling and selection protocol for determining which transmitting and receiving antenna sectors provide the desired signal is the signal amplitude. However, using signal amplitude alone does not ensure that the transmission path selected is the optimum path.
Therefore, a need exists for a communication system which utilizes directive beam antennas and which selects the proper transmission path based upon signal amplitude, signal interference and multipath distortion. Moreover, a need exists for a low cost directive beam antenna array for utilization in the communication system.